The present disclosure relates to a frequency modulated continuous wave (FMCW) radar.
An FMCW radar is known as a type of distance measuring radar. An FMCW radar continuously transmits a signal with a frequency varying with time, and receives a reflected wave from an object. The radar can measure the distance to the object and its moving velocity by analyzing the reflected wave. Such a radar includes a transmission system and a reception system. In a radar of this type, however, a signal sometimes leaks from the transmission system to the reception system, resulting in a lower measurement precision. In particular, as a circuit with such a radar decreases its overall size, the distance between the transmission and reception systems also decreases. As a result, the leakage signal comes to have an even more significant negative effect on its performance.
According to a known technique, a receiver supplies an FM signal to a mixer through a delay device causing the same amount of time delay as that of a leakage signal component from a transmission system to a reception system, thereby converting the leakage signal component into a direct-current (DC) component. Then, the receiver further removes the DC component to attempt to cancel the leakage signal component (see Japanese Unexamined Patent Publication No. H11-183600).